perf(component): render initial diff during SSR

[jaysin586]

Summary

Render the initial diff in server HTML so useful content is available before
hydration and with JavaScript disabled. Diff computation is now derived and
pure, while onProcessing remains a client-only effect with stable raw-diff
identity across callback-only changes.

Changes

• ✨ Add SSR-visible derived diff computation without changing public props or callback arguments
• 🧪 Add a loud 005 diagnostic with no-JavaScript server-markup and hydration coverage
• ⚡ Preserve the compact default and compact={false} legacy DOM through hydration
• 🛡️ Record independent guard checkpoints and cap the full 110-test matrix at two workers to protect fixed timing ceilings from browser contention

Verification

• 005 Chromium gate passed three consecutive 2/2 runs
• Targeted Chromium passed 17/17
• Library tests passed 78/78
• Svelte check reported zero errors and warnings
• Package build and publint passed
• Scoped Trunk format/lint passed
• Full five-project matrix passed 110/110 three consecutive times with two workers: 59.3s, 50.7s, 51.6s

Commits

• e9a6241 docs(plan): align SSR work with compact default
• 8b8473a perf(component): render initial diff during SSR
• 266eb52 docs(plan): record SSR guard blocker
• 2d47709 docs(plan): stabilize SSR full-matrix gate

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch advisor/component-perf-005-ssr-diffs

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